What Ah capacity should a UPS battery have? (Sizing)

Required battery capacity, by dividing the energy required by the load by the battery voltage and discharge depth bulunur: Ah = (Yük × süre / verim) / (V × DoD). Örneğin 20 kW yük, 30 dk, 384 V, %80 DoD, %90 verim için ≈ 36 Ah (dizi başına) gerekir.

Energy = Load × Time / Efficiency · Ah = Energy / (V × DoD)
Example calculation: 20 kW yük, 30 dk, 384 V, %80 DoD, %90 verim → enerji ≈ 11,1 kWh; Ah = 11.111/(384×0,8) ≈ 36 Ah (dizi başına).

UPS Battery Sizing (Required Ah)

Calculate the battery capacity (Ah) required for the desired autonomy time. This is the reverse of the UPS autonomy tool: it gives the time and finds the capacity.

Required capacity
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Required energy
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Notes: Required energy = Load × time / efficiency · Ah = energy / (V × DoD). The result is for a battery string. The Peukert effect (capacitance drop at high current) has been neglected; The actual value varies depending on battery age and temperature, and is verified by a discharge test.
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How is it calculated?

  1. Enter the load (kW) and the desired autonomy (minutes).
  2. Enter the battery DC voltage (V) and discharge depth (DoD %).
  3. Enter the inverter efficiency and click Calculate.

Frequently Asked Questions

How to size a UPS battery?
The energy that the load will draw over the desired period is calculated and divided by the battery voltage and discharge depth to find the required Ah.
What is DoD (depth of discharge)?
DoD is the percentage of the battery that can be safely discharged; a higher DoD requires less Ah but shortens battery life.
Does the calculated Ah give the actual duration?
It's an approximation; the Peukert effect, battery age, and temperature can shorten the actual lifespan — confirmed by discharge testing.

Related tools and services

This tool and its content are for general informational purposes only; they do not constitute a binding inspection/declaration of conformity. Definitive results will be determined through on-site inspection in accordance with relevant legislation and standards. Get a quote →